Gemini 2.5 Flash doesn't respond at all when using tools (Native Function Calling) works fine with Groq
Hey everyone, running into a strange issue with Open WebUI and hoping someone has seen this before.
Setup:
- Open WebUI (Docker, self-hosted)
- Gemini 2.5 Flash connected through the official Google API
- Function Calling set to "Native"
- A few builtin tools enabled (knowledge base, memory, notes, calendar, etc.)
- A knowledge base attached to the model for RAG
The problem:
Whenever I ask something that requires the model to use a tool (like searching my knowledge base), the chat just goes completely silent. No response, no error message, nothing. It just sits there.
If I ask something simple that doesn't need any tool, it responds normally without any issue.
I switched the same setup to use Groq instead (same tools, same knowledge base, same system prompt) and it works perfectly every time. So it really seems tied to Gemini specifically.
I also tried switching Function Calling from "Native" to "Default", and that got responses working again, but now the model sometimes reveals tool-calling code/syntax directly in the chat instead of using it silently and giving me a clean answer.
Has anyone run into this with Gemini specifically? Is this a known limitation, or something I can fix on my end (settings, prompt, number of tools enabled, etc.)? Any pointers would be appreciated, feeling a bit stuck on this one.
Thanks in advance!